To develop the most highly specific anti-ERCC1 monoclonal antibody with a protein microarray chip. A. Specificity evaluation with a protein microarray chip. The overexpression protein microarray chip was immunostained with the 4F9 clone. This data shows that 4F9 is highly specific to ERCC1 (indicated with red arrows). No cross-reactivity was observed with any other test protein. B. Western Blot confirmation analysis. Seven OriGene VERIFYTM overexpression lysate antigen standards (Lane 1 to 7) were fractionated on SDS-PAGE, and then immunoblotted with 4F9. The recombinant protein expression levels for the each of the different protein overexpression lysates were confirmed with the anti-DDK antibody (Figure 2B). Lanes 1 to 7 are loaded with samples for ERCC1 (NM_202001), ERCC1 (NM_001983), ERCC2 (NM_000400), ERCC3 (NM_000122), ERCC4 (NM_005236), ERCC5 (NM_000123) and PCYT1A (NM_005017).